Patent GB-1240465-A (GB)
Title: Improvements in or relating to tube pressure filters
Inventor: GWILLIAM RALPH DEREK
IPC: B01D37/04
Filed: 1967-06-29
Abstract: 1,240,465. Press filter. ENGLISH CLAYS LOVERING POCHIN & CO. Ltd. 1 July., 1968 [29 June, 1967], No. 30158/67. Heading B1D. A press filter consisting of inner and outer cylindrical shells 20, 1, defining therebetween an annular space divided into inner and outer compartments by an inflatable sleeve 10 secured to the outer shell, the inner shell being perforate and supporting filter element 29, 30, is characterised by a lower inlet 24 coacting with annular, perforate baffle 27, which spreads slurry pumped in at 25-30 p.s.i.g. around the circumference of inner compartment X and causes it to scour the lower part of the filter element. Just before and while compartment X is being filled, hydraulic fluid comprising a glycerol-water mixture of specific gravity within 0.05 of the clay or chalk whiting slurry is pumped into compartment Y through inlet 11. The hydraulic fluid pressure is subsequently increased to between 1000 and 10,000 p.s.i.g., forcing sleeve 10 radially inwards to squeeze the liquid content of the slurry into the shell 20 whence it is removed by siphon 26. Ram 34 subsequently lowers shell 20 axially out of shell 1, and three short blasts of air delivered into shell 20 by inlet 25 blow the filter cake, 0.2 to 0.3 inches thick, from the filter element. Annular baffles 27, 28 cover the hose clips which secure the ends of the filter element to the shell 20. The filter element in Fig. 1 comprises a coarse backing cloth 30 of polyvinylidene chloride and a fine cloth 29 of hot calendered polyethylene terephthalate, continuous filament multi-ply yarn. The ends of the element are caulked with silicone rubber and wound with polyvinyl chloride tape. Other suitable filter media are nylon, singed woollen felt and cotton cloth. In Fig. 6 (not shown) a wire mesh sleeve may support or replace the backing cloth, and the slurry inlet (124) opens into a chamber (151) which communicates with compartment X via radial channels (132), whose outer ends are closed by a resilient ring (152) acting as a non- return valve. This embodiment also involves an alternative end clamp for the filter element. Fig. 7 (not shown) illustrates another slurry inlet circuit (224, 232, 252) with a non-return valve, and a more elaborate hydraulic fluid inlet. Embodiments also differ in the arrangements of sealing rings 6, 7 between the two shells, which may be dispensed with altogether or located on either shell. Fig. 2 shows the press A with its hydraulic fluid delivery pump B, suction pump D for withdrawing the fluid after pressing and slurry delivery pump E, with associated valves and reservoirs. The various steps of the operation cycle may be controlled by a series of camoperated solenoids (Fig. 3, not shown) controlling each unit individually, or by a fluid logic circuit (Fig. 5, not shown) wherein each step is initiated on completion of essential preceding step(s) by suitable NOT, NOR and FLIPFLOP gate circuits. The press is particularly suitable for slurries containing more than 20% particles below 20 microns in size.